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Biomedical subjects

N Ishiguro

Publications and source records attributed to N Ishiguro.

At least 145 records · Page 8Linked to original sources
PubMed1992

Characterization of the stage(s) in the virus replication cycle at which the host-cell specificity of the feline parvovirus subgroup is regulated in canine cells.

Feline panleukopenia virus (FPLV), mink enteritis virus (MEV), and canine parvovirus (CPV) are classified as a host-range variants. They show different host-range specificity in vivo and host-cell specificity in vitro. For instance, FPLV and MEV cannot grow or can grow only inefficiently in canine cell lines such as MDCK and the canine fibroma cell line A72. Here we have studied the mechanism(s) by which the different cell tropism is mediated in vitro. When FPLV or MEV was inoculated to A72 cells, viral DNA replicated slightly, few viral-antigen-positive cells were detected, and the culture fluid contained the threshold level of infectivity. On the other hand, when an infectious molecular clone of MEV (pMEV) was introduced into A72 cells, viral DNA replicated efficiently, and the culture fluid of pMEV-transfected cells contained much higher infectivities than that of MEV-infected cells. In spite of the restrictive growth in A72 cells, MEV could bind to A72 cells as efficiently as CPV. No detectable viral RNA was produced in MEV-infected A72 cells. In contrast, efficient viral transcription occurred in pMEV-transfected A72 cells. These results suggest that the restrictive infections of MEV and FPLV in A72 cells are not mediated by the attachment of the virus to the cells or by the events occurring after the viral transcription. It appears to be caused by the stage(s) in the virus replication cycle, which exists between a postadsorptional step required for virus penetration and the initiation of viral transcription.

Aleutian Mink Disease Virus↗
PubMed1992

Molecular analysis of a HTLV-IpX defective human adult T-cell leukemia.

Fresh and cultured leukemia cells from an adult T-cell leukemia (ATL) patient which possessed gag and env gene defective human T-cell leukemia virus type I (HTLV-I) provirus genome were molecularly analyzed. Cells from both fresh and the established cell line, named KB-1 showed identical surface markers of helper T cells, expressed the interleukin 2 (IL-2) receptor and had an identical defective HTLV-I provirus genome with deletions of the gag and env genes involving pX gene exon 2. The KB-1 cells grew vigorously in vitro, even in the absence of IL-2 and the culture supernatant of KB-1 contained a large amount of IL-2. Neither pX mRNA nor p40(TAX) protein was detected in the KB-1 cells. The collective evidence suggests that the pX gene was not functioning in this particular ATL case. The biological function of the HTLV-I genes, especially the pX gene is discussed in relation to the early and late leukemogenesis of ATL.

Blotting, Southern↗
PubMed1992

Biological activity of subfractions from scrapie-associated fibrils.

Subfractions, a nucleic acid fraction and a PrP fraction consisting of PrP17-25, a core fragment of PrPsc, were prepared from the scrapie-associated fibril-enriched fraction from scapie-affected mouse brains. The nucleic acid fraction consisted mainly of variously fragmented DNA and no scrapie-specific nucleic acid was detected in the fraction by SDS polyacrylamide gel electrophoresis. To examine the biological activity, the nucleic acid fraction was either first introduced into mouse L-929 cells before or after nuclease treatments, then transfected cell lysates prepared 2 weeks later were inoculated into mice, or directly inoculated into mice with or without the PrP fraction. The PrP fraction alone was also inoculated into mice. Mice inoculated with the transfected cell lysates or with the nucleic acid fraction alone showed no scrapie signs during their lifespan or the observation period. While 60% of the mice inoculated with the PrP fraction alone and 67% of those inoculated with the fraction together with the nucleic acid fraction showed clinical signs of scrapie. A nucleic acid molecule bound covalently to PrP17-25 was not detected. The results obtained by the present procedures so far suggest scrapie infectivity to be associated with PrPsc, which does not contain any detectable scrapie-genome molecule as either free or covalently bound nucleic acid.

Animals↗
PubMed1992

Reperfusion injury in bone: effects of CV-3611, a free radical scavenger, on ischemic revascularized bone grafts in rats.

Oxygen-derived free radicals have been shown to play an important role in reperfusion injury. The protective effect of CV-3611, a new free radical scavenger, on reperfusion injury in an ischemic revascularized hind limb model in rats was examined. Warm ischemia (25 degrees C) was produced by vascular pedicle clamping and sustained for 0, 3, and 6 hr. Histologic and fluorochrome bone-labeling analyses demonstrated improved overall viability of osteocytes, osteoblasts, and marrow cells in the CV-3611-treated group compared to controls. The CV-3611-treated group had statistically significant improvement in the ratio of lacunae, maintained osteogenetic ability, and preserved normal growth plate architecture after 6 hr of ischemia. The control group showed local central areas of disorganization by 3 hr and complete destruction of the growth plate with early growth arrest after 6 hr of ischemia. These results indicate that administration of CV-3611 prior to reperfusion can prevent reperfusion damage in bone tissue and maintain osteogenetic ability. This technique may have clinical application for reducing the complications of prolonged ischemia to bone tissue.

Animals↗
PubMed1992

Surgical excision of hemophilic pseudotumor of the ilium.

The iliac hemophilic pseudotumor is a rare complication of hemophilia occurring in 1-2% of patients with Factor VIII or Factor IX deficiency. It is frequently disabling and life threatening. This report presents a comparative study of postoperative results of two cases of hemophilic pseudotumor of ilium. One patient undergoing partial resection showed a favorable postoperative course, whereas the patient with complete resection of the pseudotumor died of postoperative bleeding and sepsis. Studies on the postoperative results of these two cases indicate that careful preoperative consideration of tumor size and degree of infiltration is of the utmost importance in operative management. Early excision of tumors eliminates the possibility of endogenous infection. Even partial resection of huge tumors, leaving the lateral wall intact for compression, can promote recovery of functions.

Angiography↗
PubMed1991

Pre-clinical and clinical diagnosis of scrapie by detection of PrP protein in tissues of sheep.

The usefulness of detecting the scrapie-associated fibrillar protein (PrP) in the lymphoreticular organs of sheep as a diagnostic tool was investigated. The PrP was detected by means of a rabbit-anti-sheep PrP polyclonal antibody by Western blot analysis. PrP was detected in samples from the central nervous system (CNS) of five of six sheep showing clinical signs of natural scrapie infection, in spleen samples from four of the six sheep and in lymph node samples taken from three of the sheep. PrP was detected in the spleen and lymph node samples, but not in the CNS samples from one of the six sheep that was clinically and histopathologically abnormal. This animal appeared to be in the early clinical stage of the disease. A total of 47 clinically normal sheep were examined for the presence of PrP. It was detected in spleen samples from three of the 47 sheep and in lymph node samples from three of the 39 sheep tested. Similarly, PrP was detected in a sample of lymph node obtained surgically from one of three experimentally infected sheep 14 months after inoculation. The PrP-positive sheep and one of the remaining PrP-negative sheep showed clinical signs of scrapie six and five months later respectively. One sheep euthanased 18 months after experimental infection was positive for PrP in the CNS, spleen and lymph node, but five other sheep which were killed or died two, eight, 16, 18 and 21 months after infection were negative or doubtful for the detection of PrP.

Animals↗
PubMed1991

Morphological and biochemical evidence that scrapie-associated fibrils are derived from aggregated amyloid-like filaments.

The membrane fraction from scrapie infected mouse brains was dissolved in saturated urea, centrifuged on a 10 to 50% glycerol gradient at 35,000 rpm for 24 h, and fractionated from the bottom of the tube into 11 fractions. PrP was detected throughout the gradient. However, the relative PrP concentrations of fractions 4 and 8 were the highest. The relative PrP concentration versus protein concentration of fractions 1 to 4 was higher than that of the other fractions. Scrapie infectivity also was detected in all fractions. Fractions 2, 3, 4, 7, and 8 produced the shortest incubation periods. Positively stained filamentous aggregates with sizes varying from about 40 x 60 nm to more than 4 microns were observed in fractions 2 and 4 by negative staining. These resembled amyloid filaments. Congo red-stained aggregates showed birefringence under polarized light. Aggregation of the filamentous aggregates was observed by incubation with anti-mouse SAF serum. Fine fibrils 10-18 nm in width were partially dissociated from the aggregates by brief exposure to the detergent Sarkosyl. These facts suggest that SAF are not products of self-assembly from subunit structures liberated from membranes by exposure to detergent, but exist as aggregates of amyloid-like filaments from which SAF are dissociated by detergent extraction.

Animals↗
PubMed1991

Effects of dietary Ca2+ on erythrocyte Na(+)-transport systems in spontaneously hypertensive rats.

1. The purpose of this study was to determine the effect of dietary Ca2+ intake on blood pressure and erythrocyte Na+ transport in spontaneously hypertensive rats. 2. Spontaneously hypertensive rats and Wistar-Kyoto rats were fed diets with three different Ca2+ contents, 0.1% (low-Ca2+ diet), 0.6% (normal-Ca2+ diet) and 4.0% (high-Ca2+ diet), between 6 and 20 weeks of age. At 20 weeks of age, the levels of erythrocyte Na+ efflux, as well as Na+ and K+ contents in erythrocytes, were measured. 3. On the low-Ca2+ diet, spontaneously hypertensive rats showed an enhancement of hypertension. Conversely, on the high-Ca2+ diet, they showed an attenuation of the increase in blood pressure. Spontaneously hypertensive rats had a lower erythrocyte Na+ content and increased activity of the Na+ pump at higher levels of dietary Ca2+. Passive Na+ permeability and Na(+)-K+ co-transport were similar in spontaneously hypertensive rats on the low-, normal- and high-Ca2+ diets. There were no significant differences in blood pressure and in Na+ pump activity in WKY on the three different diets. 4. It is concluded that dietary Ca2+ might affect the regulation of blood pressure in spontaneously hypertensive rats by changing the activity of Na+ pump in the cell membrane.

Animals↗
PubMed1991

Nerve regeneration in rat composite-tissue allografts.

Reinnervation of composite-tissue allografts was examined in a rat hind-limb transplant model under Cyclosporin A (CyA) immunosuppression. Two groups of animals were studied. Group 1 consisted of 10 composite-tissue allografts using inbred Fisher rats (F344) as recipients and inbred Lewis rats (LEW) as donors. Recipient animals received 15 mg/kg/day CyA subcutaneously for three weeks and then twice weekly for three months. Group 2 consisted of 10 composite-tissue isografts undergoing no immunosuppression, and using F344 as both donors and recipients. Eight months after operation, electromyographic, histologic, and morphometric assessments of nerve regeneration were made. There were no significant electromyographic differences between these two experimental groups in amplitude and conduction velocity, but the levels were lower than in controls. The histologic patterns of nerve regeneration within the composite-tissue transfers were similar in the two groups. However, the fiber population in the regenerated nerves in the two groups was different from that in the normal sciatic nerve. This study confirmed the reinnervation of composite-tissue allografts under CyA immunosuppression. The quality of regeneration in allografts was similar to that in isografts, but the histologic and electromyographic properties of regenerated nerves were different from those of normal sciatic nerves.

Animals↗
PubMed1991

Cloning and nucleotide sequence of the gene (citA) encoding a citrate carrier from Salmonella typhimurium.

A cryptic citrate transport gene (citA) from Salmonella typhimurium chromosome was cloned and its nucleotide sequence was determined. The cloned plasmid conferred citrate-utilizing ability on wild-type Escherichia coli, which cannot grow on citrate as the sole source of carbon. The resultant E. coli transformant was able to transport citrate. A 1,302-base-pair open reading frame with a preceding ribosomal binding site was found in the cloned DNA fragment. The 434-amino-acid protein that could be translated from this open reading frame is highly hydrophobic (69% nonpolar amino acid residues), consistent with the fact that the transport protein is an intrinsic membrane protein. The molecular weight of this protein was calculated to be 47,188. The gene sequence determined is highly homologous to those of Cit+ plasmid-mediated citrate transport gene, citA, from E. coli, the chromosomal citA gene from Citrobacter amalonaticus and the chromosomal cit+ gene from Klebsiella pneumoniae. The hydropathy profile of the deduced amino acid sequence suggests that this carrier has 12 hydrophobic segments, which may span the membrane lipid bilayer.

Amino Acid Sequence↗
PubMed1991

Changes in subgenome types of adenovirus type 4 isolated from patients with ocular disease between 1985 and 1989 in Sapporo, Japan.

A total of 122 adenovirus type 4 (Ad4) strains isolated from patients with epidemic keratoconjunctivitis at an eye clinic in Sapporo, Japan, from 1985 to 1989 were identified as Ad4a. By the use of HinfI and TaqI restriction endonucleases, these Ad4a strains were classified into 12 subgenome types. During this observation period, two epidemics of Ad4 infection relating to epidemic keratoconjunctivitis occurred. During the Ad4a epidemic in 1985, three subgenome types became predominant successively. However, except for one strain, the prevalent strains isolated during the epidemic of Ad4a in 1988 all belonged to a single subgenome type. In the years when an Ad4a epidemic was not observed, such Ad4a strains were new or previous subgenome types. The prevalent subgenome types tended to change within several years.

Adenoviruses, Human↗
PubMed1991

Effects of dietary calcium on erythrocyte sodium ion transport systems in spontaneously hypertensive rats.

The alteration of sodium ion transport in red blood cells was observed in SHR and patients with essential hypertension. The purpose of the present study was to determine the effects of dietary calcium intake on blood pressure and sodium ion transport of red blood cells in SHR. The SHR were fed a diet with three different levels of calcium contents as follows: 0.1% (low), 0.6% (normal) and 4.0% (high) of calcium between 6 and 20 weeks of age. At 20 weeks of age, the levels of erythrocyte sodium efflux, sodium or potassium contents in the red blood cells were measured. On the high Ca diet, SHR showed an attenuation of the increase in blood pressure. On the low Ca diet, SHR showed an enhancement of hypertension. In proportion of increasing of dietary calcium contents, SHR had a lower level of sodium content in the RBC and a higher activity of the sodium pump. However, the passive sodium permeability and sodium-potassium cotransport in SHR were similar among the three different Ca diets. It is concluded that the amounts of dietary Ca might be related to the regulation of blood pressure by changing the sodium pump of the cell membrane in SHR.

Animals↗
PubMed1991

Preservation of skeletal muscle in tissue transfers using rat hindlimbs.

Replantation of major extremities after long periods of ischemia can lead to viable replants in many cases, but functional restoration is often poor owing to fibrosis of the muscle. In this study, maximum hypothermic time in tissue transfers containing skeletal muscle using hindlimbs of Lewis rats preserved in 4 degrees C Euro-Collins solution was investigated. After preserving midthigh amputated legs in this solution for 6, 9, and 12 hours, the legs were transplanted to other inbred rats using microsurgical technique, and 1 week later, gastrocnemii were obtained to analyze ATP, ADP, and AMP using high-performance liquid chromatography. The values were compared with those for healthy legs, nonischemic operated control legs, and legs preserved in the same manner for 6, 9, and 12 hours. Histologic and serologic examinations were conducted. ATP values of the 9-hour preservation group resumed those of the nonischemic operated control group, with the values of the 12-hour preservation group remaining at 61 percent. Histologically, focal necrosis, hyaline degeneration, and regeneration processes were the most characteristic manifestations in the muscles transplanted after cold ischemia of 12 hours. It was concluded that skeletal muscle could be preserved for 9 hours in 4 degrees C Euro-Collins solution.

Adenine Nucleotides↗
PubMed1990

Primary structure of bovine lactate dehydrogenase-A isozyme and its synthesis in Escherichia coli.

Eleven cDNA clones encoding lactate dehydrogenase(LDH)-A isozyme were isolated from a bovine lymphocyte cDNA library, and the nucleotide sequences of three of the clones (pLDH5, pLDH9 and pLDH12) were determined. With the exception of variation in the 5' portion, two cDNA clones (pLDH9 and pLDH12) appeared to contain the full-length cDNA of 1786 bp, consisting of the protein-coding sequence (996 bp), the 5'- and the 3'-untranslated regions and the poly(dA) tail. The predicted amino acid (aa) sequence of bovine LDH-A (332 aa) showed 96.7% homology with that of pig LDH-A. The protein-coding cDNA region (1650 bp) was inserted into an Escherichia coli expression vector ptac11 and expressed. The protein synthesized in E. coli showed enzyme activity of LDH and was identified by cellogel electrophoresis as LDH-5 isozyme whose subunit M chain is the product of the LDH-A gene.

Amino Acid Sequence↗
PubMed1990

Sequence and diversity of bovine T-cell receptor beta-chain genes.

The nucleotide sequences of 38 T-cell receptor (Tcr) beta-chain cDNA clones which were isolated from a cDNA library (2 x 10(6) plaques) constructed from bovine peripheral blood lymphocytes were determined. Of 38 cDNA clones, 22 were rearranged and contained the functional variable (V) gene segments. These clones were tentatively divided into nine Tcrb-V gene families which correspond to the human Tcrb-V family. Among them, a Tcrb-V12 gene segment was isolated from 9 out of 22 clones, suggesting that this Tcrb-V family was expressed in the bovine peripheral blood lymphocytes. Two different constant (C) gene segments were found, and both C regions were composed of 178 amino residues. The amino acid sequences of bovine Tcrb-C regions are approximately 80%-82%, 78%, and 78% similar to those from human, mouse, and rabbit, respectively. To estimate Tcrb-V-associated restriction fragment length polymorphisms (RFLPs), Southern blot analysis was performed using liver DNAs from four bovine breeds, Holstein, Angus, Hereford, and Japanese Black. However, no significant difference was observed among genomic DNAs of Tcrb-V loci from these four breeds.

Amino Acid Sequence↗